Heating with Solar

• Parts. Complete list of parts needed for Solar Air Heater, including options for power source variations.
• Manual. Directions for constructing Direct Solar Air Heater.
• Examples. Various applications of Solar heater panels sites.
• Conservation. Energy saving tips and weatherizing.

Introduction

Solar heating is simple, cost effective, virtually maintenance free and environmentally sound. This system is designed to work as supplemental heat.

The manual is for an active direct air solar heater. It is an ‘active’ system because it is using an electric fan to move the air. It would be ‘passive’ if the air was transferred by convection and used no added power source to move the air. It is “direct” because this unit will be heating the air directly as opposed to radiant heating that would heat a thermal mass storage area in the floor.

This solar heater is simple and highly effective. There are 3 physical layers and 2 air spaces and the transfer box/window unit.

The top layer is:

• 1. Glazing- plexiglass, tempered glass or polycarbonate
• 2. Air space- this 2” to 3” space stays constant, the air does not move in or out of this part of the unit.
• 3. Absorber plate- made of aluminum with a coating to help absorb the solar radiation
• 4. Air space- this 1’ to 1 ½” space is baffled and moves air into and out of this space by a fan.
• 5. Base structure- made of plywood and insulated or not with ½’ fiberglass.
• This panel is then connected to the window unit or ducting system that carries the air into the building.

• Solar thermal energy passes through the transmissive glazing and is contained in the upper space. The thermal radiation is absorbed by the plate and transferred to the lower air space and the fan pushes the air through and out the space in to the building. By having a stationary air space, you do not have to constantly reheat the air above the absorber plate. The air cavity below the plate is in constant contact with a continuous heat source.

• Solar heating system must be oriented towards the south and have no obstructions on its path across the sky. The optimum angle to the sun is + or – 15 degrees of your latitude. For instance, Amarillo, Texas is at about 35 degrees latitude, so in :

We built both a 45 degree angled version of the panel and a vertical version. Because of ease of constructing and figuring a 45 degree angle we compromised on the efficiency. Although for two months of the winter the angle is just right. The advantage of the vertical unit for this area is that you do not have to take it down or cover because of the sun’s angle in the summer months. Although you may loose as much as 15% efficiency, we recommend that you compensate by making your unit larger if you choose to go with the vertical type. Also, vertical units have more protection from the spring and summer hail storms. You don’t have to cover or remove the vertical unit in the heat of the summer or protect it from bad weather.

Things to consider.

• Where is the window you want to put the unit in? Are you using vertical or horizontal positioning? Do you want a slanted or vertical unit? How much money do you want to spend? How much space do you want to heat? What will be your power source, solar PV, AC or DC. How many sections will you need to use?
• Where will you need to place the vent holes? What type of thermostat do you want to use? Wood or metal frame? What type of glazing will you use? Do you want to make this as a direct air or as radiant heat in a crawl space or rock storage under the floor.
• Solar heating is different that conventional heating units. Normally when the air gets cold in the house the thermostat switch turns on the heater blower, it warms up the space and then the switch disconnects and the unit turns off. With a solar unit, when the thermal switch gets to the designated temperature, for instance 90 degrees, this activates the fan. If the temperature stays above the setting the fan will stay on. Which means if the sun is out the unit will be on all day until it cools off at night or until it gets warm enough in the morning. If the interior of the building gets too warm you simply ventilate the space by opening doors and windows. It is best on these window units to not turn the unit off. It can put undue stress on the structure through heat build-up.